1. Field of the Invention
The present invention relates to an image forming apparatus which processes data input by a user and outputs the data on paper. More specifically, the present invention relates to a device which selectively uses consumables of the image forming apparatus to satisfy particular demands of the user, and a method of optimizing the use the consumables.
2. Description of the Related Art
Image forming apparatuses such as printers, photocopiers, and facsimile machines generally include a plurality of removable parts held in a single casing. For example, an electrophotographic printer comprises a developing roller, a toner cartridge, a transfer roller, all of which are removable. Therefore, each of the parts can be replaced with a new one whenever necessary. This can occur, for example, when the life span of any of these parts has expired. These parts are generally called ‘consumables’.
Referring to FIG. 1, a laser beam printer will now be described as an example of general image forming apparatus. The general laser beam printer 100 is comprised of a video part unit 110 and an engine control unit 130. The video part unit (video unit) 110 converts data received from an external device, such as a host computer, into image data of a bitmap format. The engine control unit 130 controls the operation of an engine mechanism 150 in printing the image data by control of the video unit 110.
The video unit 110 and the engine control unit 130 are usually operated by a single processor. The single processor usually is a microprocessor in a central processing unit (CPU), which supports a multi-process operating system (OS), and is provided in a main control unit 117. Accordingly, the video unit 110 and the engine control unit 130 are provided in a single printed circuit board (PCB). For the engine control unit 130, an application specific integrated circuit (ASIC) is typically used, which comprises a memory 132 for storing status information of the engine mechanism 150. The engine control unit 130 controls the operation of the engine mechanism 150 by the main control unit 117.
The engine control unit 130 is directly connected to the CPU 118 in the main control unit 117 through a system bus 120. The system bus 120 comprises an address bus, a control bus, and a data bus. A bi-directional parallel bus can be used for the data bus.
The video unit 110 comprises an operation panel 119, a computer interface (I/F) 113, a memory unit 115, and the main control unit 117.
The operation panel 119 comprises an input unit which has a plurality of keys for selection or setup of functions of the laser beam printer 100, and a display unit which displays operation status information of the laser beam printer 100 by a control of the main control unit 117.
The computer I/F 113 is connected between the host computer and the main control unit 117 to interface input/output signals. For the computer I/F 113, interfaces such as an IEEE1284, a USB, and an RS232C can be employed.
The memory unit 115 comprises a read-only memory (ROM) and a random-access memory (RAM). The ROM stores control programs and a variety of application programs to operate the main control unit 117. The RAM temporarily stores the printing data received from the host computer through the computer I/F 113, and other various data generated during the execution of the programs of the main control unit 117.
The main control unit 117 is comprised of the CPU 118 which controls the operation of the video unit 110 and the engine mechanism 150 by the control programs stored in the memory unit 115. Upon receiving a file to print from the host computer through the computer I/F 113, the main control unit 117 generates a display list to convert the received data to a frame data. The main control unit 117 also compensates the color of the data into yellow-magenta-cyan-black (YMCK), and stores the compensated color data in the memory unit 115. The main control unit 117 then generates the image data of a bitmap format in respective colors out of the data stored in the memory unit 115. After the bitmap data is generated, the main control unit 117 transmits a command to the engine control unit 130 to inform it to start the printing work.
The main control unit 117 considers the engine control unit 130 as a device to control, and therefore, reads and writes predetermined information with respect to the engine control unit 130 through the system bus 120. For example, when reading the predetermined information from the engine control unit 130, the main control unit 117 reads the status information. Alternatively, when writing the predetermined information, the main control unit 117 writes the command information to the engine control unit 130.
The engine control unit 130 uses the ASIC, and controls the operation of the engine mechanism 150 by the main control unit 117, as stated above. The engine control unit 130 receives the image data transmitted from the main control unit 117 through the system bus 120, and decodes the image data. According to the result of the decoded data, the engine control unit 130 generates a pattern with respect to the image to be generated by the engine mechanism 150, and based on the pattern, controls the driving of the engine mechanism 150.
The engine mechanism 150 comprises a paper supply unit 151, laser scanning unit (LSU) 152a, a LSU driving unit 152, a developing unit 153, a transferring unit 154, a fusing unit 155 and a sensing unit 156. The paper supply unit 151 picks up paper stacked in a paper supply cassette (not shown) sheet by sheet according to a paper supply signal received from the engine control unit 130. The LSU 152a forms a predetermined electrostatic latent image on a photoconductive drum (not shown) by scanning a laser beam corresponding to the image data onto the photoconductive drum. The developing unit 153 develops the electrostatic latent image by supplying toner to the photoconductive drum. The transferring unit 154 transfers the toner image formed on the photoconductive drum to the supplied paper. The fusing unit 155 fuses the toner image transferred on the paper, by heat and pressure.
The image forming apparatus described above usually checks its consumables, such as the toner, the developing roller, and the transfer roller, for the management of the lifespan, or compatibility of the consumables. Since consumables are typically applicable only to a corresponding image forming apparatus, compatibility of the consumables is quite low. Typically, therefore, a printer of a first company cannot output high quality prints using the consumables of different grades (or different companies). An exemplary embodiment to solve the above problem is disclosed in JP 2000-330432 (hereinafter, referred to as ‘Japanese prior art’), the entire contents of which are incorporated herein by reference. In the Japanese prior art, the consumables of the image forming apparatus comprise data that the apparatus can read and record, or a program module that the apparatus can execute. The program module includes a program for obtaining required conditions when using the consumables. Although the Japanese prior art enables the general use of the consumables of different models, it does not provide any method or system to enable general use of consumables of various grades in a single printer. One user may want low cost rather than high quality of the printing, while another user may demand the high printing quality in spite of high cost. To satisfy such various demands, a plurality of printers were conventionally required. Accordingly, a need exists for the image forming apparatus according the embodiments of the present invention described below, which can meet users' various demands.